Holy unpossible.This is not good, and 99,999 out of 10,000 times, you cannot get any data off without replacing the platter into a case that is working perfectly.
Put it in the freezer in a ziploc bag. Seriously, that helps sometimes. I'd try that before hitting it with a mallet.
http://lifehacker.com/5515337/save-a-failed-hard-drive-in-your-freezer-redux
If you really need to get the data, try this company...
http://www.pcrecoveryllc.com/
I used them earlier this year. They're not cheap, but they are good. And the turnaround time was fast.
It's not the disk, it's the DATA that has value.save urself alot of wasted time and go get another one.
I have a western digital 750gb desktop hard drive, it makes a clicking sound when I plug it in and my computers won't read it.
Edit: BTW, everyone should know that hard drives have a 100% fail rate. If you have important files, then make sure you run a backup of them.